The present invention relates to motor vehicle bumper systems.
A motor vehicle typically has a bumper bar supported on a body of the motor vehicle by energy absorbers which convert into work a fraction of the kinetic energy of a low speed impact on the bumper bar. Such bumper energy absorbers commonly include relatively moveable structural elements attached to the body and the bumper bar and a resistance medium between the structural elements. In a high speed impact, kinetic energy is converted into work by plastic deformation of body structure of the motor vehicle between a passenger compartment thereof and the point of impact. As motor vehicles have become more compact, however, the energy absorbing capability of the body structure of the motor vehicle has decreased as the span between the passenger compartment and the bumper bar has decreased.
A bumper energy absorber has been provided which supports a bumper bar close to a body of a motor vehicle except when sensors on the vehicle detect an impending impact. In that circumstance, the bumper energy absorber extends the bump bar out from the body to increase the span between the passenger compartment and the bumper bar and thereby increase the fraction of the kinetic energy of a high speed impact on the bumper bar that is converted into work. Exemplary outwardly extending bumpers are described, e.g., in U.S. Pat. No. 6,302,458, U.S. Pat. No. 5,967,573 and U.S. Pat. No. 5,370,429.
In accordance with a first aspect of the present invention a bumper system for a motor vehicle includes a main tubular frame rail member. An actuator is adapted to selectively extend and retract a bumper member, the actuator is mounted at least partially within the tubular frame rail member.
In accordance with another aspect of the present invention a bumper system for a motor vehicle includes a main tubular frame rail member. An additional tubular frame rail member is attached to the main tubular frame rail member. An actuator is adapted to selectively extend and retract a bumper member, the actuator being mounted at least partially within the tubular frame rail member and at least partially within the additional tubular frame rail member.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.